1. Field of the Invention
This invention relates to a digital TV (television) receiver, and especially relates to writing of a control program of the digital TV receiver.
2. Description of the Related Art
In the digital TV receiver, it is proposed that the control program is written in a rewritable nonvolatile memory such as a flash memory and rewritten according to need for updating the control program corresponding to change of service level of the TV broadcast in the future or correcting the bug in the control program (see publication gazette of examined Japanese patent application 5-56052).
Furthermore, it is proposed that a digital equipment is connected to a network for receiving programmable signals from a server, so that the control program can be updated (see publication gazette of unexamined Japanese patent application 2002-14835).
Still furthermore, it is proposed that the updated control program is superimposed on and delivered with airwaves of the TV broadcast, and the receiver extracts the control program from received signals and updates the control program (see publication gazettes of unexamined Japanese patent applications 2001-103333 and 11-275609).
When the control program of the digital TV receiver is downloaded through the network, the transmission speed is slower even though the communication pathway is stable. Thus, it is not suitable for downloading the control program of the digital TV receiver having a capacity of several mega-byte. Furthermore, a host computer such as an external server for communicating the control program is needed.
When the control program of the digital TV receiver is downloaded through the airwaves, the communication pathway is unstable, so that there is a possibility to receive the interference due to the communication error. Thus, the reliability of the received control program is lower. Furthermore, the transmission speed is not so fast. Still furthermore, it needs not only the host computer such as the external server but also cooperation of TV stations. Therefore, such the update service of the control program of the digital TV receiver cannot be offered at all areas in the world.
Still furthermore, it is necessary to memorize two control programs before and after the update, temporarily, so that two sets of flash memories are necessary, which causes the increase of the cost of the digital TV receiver. Still furthermore, it is necessary to write an initial control program into the flash memory of the digital TV receiver in a manufacturing process in a factory by another method different from receiving the airwaves. Thus, the digital TV receiver is connected to a hard disc drive apparatus through a connector so as to be written the initial control program into the flash memory, the connector and interfaces, which are not used ordinarily, are necessary.
Still another method for reading the updated control program from a recording medium such as a CD-ROM or a DVD can be considered. It, however, needs a recording medium reader which is inherently unnecessary with respect to the digital TV receiver, so that the recording medium reader causes upsizing and increase of the cost of the digital TV receiver.
For writing the control program in the manufacturing process in the factory, it is considered that the control program is written into the flash memory through a port which is inherently used for debugging a heard ware of the digital TV receiver. It, however, needs an expensive and extraordinary apparatus such as an in-circuit emulator. Furthermore, it requires careful treatment for activating the system stably, since the flash memory is disposed at a delicate portion near to a CPU core and it can easily be affected by external noises.